01626564

Component

Concrete-filled steel tubes (CFSTs) and reinforced concrete-filled steel tubes (RCFSTs) are used in bridges as piers, piles or shafts. Prior research indicates that CFSTs have flexural strength and stiffness capacities that exceed structural steel and reinforced concrete components with similar diameters and steel amounts. However far fewer research studies have evaluated the shear strength of CFSTs or RCFSTs. Most codes adopt one of two approaches to compute their shear capacity assuming the steel alone contributes to the shear strength, neglecting the concrete, or a combination of the steel tube and concrete contribute. Evaluation of those equations using prior test results (typically performed on small-scale tubes approximately 150mm or 6 in. in diameter) indicate that current expressions greatly underestimate the shear capacity. A research program was undertaken to investigate the shear capacity of large-scale (508mm or 20 in. diameter) tubes. A range of design parameters were studied including aspect ratio (a/D), diameter-to-thickness ratio (D/t), concrete compressive strength, tube type, tail length and interface condition. The results were used to quantify shear failure and combined with prior research meeting the shear-failure definition to develop a new shear capacity expression for CFSTs and RCFSTs.

This paper was sponsored by TRB committee AFS30 Standing Committee on Foundations of Bridges and Other Structures.

01618707

17-05072

English

14p

2017

Transportation Research Board 96th Annual Meeting

Digital/other

Figures; Photos; References; Tables

Bridge design; Reinforced concrete; Shear strength; Steel; Tubing

Bridges and other structures; Design; Highways

Transportation Research Board Annual Meeting 2017 Paper #17-05072

TRIS, TRB, ATRI

Dec 8 2016 11:57AM